Study On Coupling Of Seepage And Stress On Boreholes Under The Influence Of Drilling Fluid

Coupling analysis on unsteady seepage and stress in fractured rock masses is a very valuedtask for discussion. With the changing of boundary hydra-head, the width of the fractureincreased or reduced, which affects the fracture flow. Conversely, the change of seepage fieldaffects the stress field. The interaction of the two filed is called coupling. The seepage in rockmass mainly reflected as fracture flow. To establish the relationship of the hydraulicconductivity and stress field is to describe the coupling interaction of seepage and stress. Basedon the previous theory research in the field of seepage-stress coupling and the background ofdrilling engineering as well, the finite element method is used in the iterative analysis of theseepage-stress coupling upon the coupling of seepage and stress in borehole rock mass with theseepage field influenced by drilling fluid. The thesis has carried out the following researchworks:1. The coupling model of seepage and stress interaction on rock mass without fractures.On the basis theory of fluid mechanics, elastic-plastic mechanics and rock mechanics,according to the basic theory of flow-solid coupling theory, the equations of seepage-stresscoupling is established. The interaction relationship of coupled equations is based on theprinciple of effective stress, and the definite condition is also given.2. The coupling model of seepage and stress interaction on rock mass with one fractureand numerical example validation. The permeability of fractured rock mass is described. Andbased on the study of the permeability of single fractured rock mass and its deformationmechanism, the coupling model is set up. Using the finite element software, a dam seepage-stress coupling effect is analyzed. Taking the coupling equation of permeability coefficient andthe normal stress in negative exponential function, the dam is analyzed with two conditions ofwithout fracture and with one single fracture.3. The coupling interaction of seepage-stress in borehole rock mass under the effect ofdrilling fluid and the analysis of engineering example of GHX-106borehole. The stress fieldaround borehole is analyzed, and the stress models around borehole with the effect of drillingfluid are established. Taking the GHX-106borehole as an engineering example, the parametersneeded by the numerical calculation of seepage and stress coupling are gotten. Horizontalsection and vertical section numerical calculation model of borehole are established, the modelsare also analyzed with two conditions of without fracture and with one single fracture. Thecalculation results of GHX-106borehole of horizontal section numerical model and the verticalsection model at200m depth are consistent, which we can conclude that the analysis results arescientific and reliable.